As in so many other industries, robots have been marching into Wall Street for years. That’s especially the case in stock trading, where algorithms now do the majority of buying and selling. Instead of a boisterous trading floor, these days many US equity transactions happen in a data center in suburban New Jersey. One place where human traders are safe, though, is the New York Stock Exchange, which has roots going back two centuries. The stock exchange has made sure its human presence is...